1. Field of Invention
This invention relates to a method for detecting damaged currency. In particular, the invention relates to a method that detects a degree of deterioration of damages bills or paper money.
2. Description of Related Art
It is well known that paper money is a popular form of consideration that is exchanged for goods and/or services. Individual pieces of paper money are commonly referred to as bills. As time progresses, a bill in circulation is vulnerable to various types of damage. For example, a bill can become dirty, torn, worn-down and/or wrinkled. In addition, over time, the print design on the bill gradually fades and the print ink wears off.
Typically, a consumer will tender paper money to a cashier or the like as a form of payment when purchasing an item. However, recently there has been a trend where consumers can avoid waiting in cashier lines and interact directly with a kiosk having an automatic bill-handling machine to carry out the transaction. Unfortunately, damaged bills jam the automatic bill handling machines, causing the machines to stop working. Accordingly, because removing the jammed bill from the automatic bill handling machine requires a substantial amount of time, reducing jamming occurrences has become an important problem that bill-handling machine manufacturers have been trying to solve.
Globally, the recognition of damaged bills is an important problem for banks so that the damaged bills can be identified and removed from circulation.
Because the need for a method of detecting damaged bills is widespread, a number of conventional methods for detecting damaged bills have been developed. An example of a known method preferred by some bill handling machine manufacturers uses an ultrasonic wave method to identify and separate the damaged bills from undamaged bills. However, the ultrasonic wave method is only suitable for "soft" bills, such as a very fatigued or worn-out bill.
A majority of the remainder of these conventional methods discriminate damaged bills from undamaged bills using non-contact optical methods. One non-contact optical method recognizes whether a bill in circulation, i.e., a test bill, is a damaged bill or an undamaged bill by detecting a reflected light intensity and a transmitted light intensity for the test bill when the test bill is illuminated and scanned. This non-contact optical method then determines an evaluation value from the detected reflected and transmitted light intensities of the test bill. The evaluation value for the test bill is then compared to corresponding pre-determined evaluation values obtained for a normal or reference bill to see if the evaluation value of the test bill falls within established statistical parameters for an acceptable bill. If the evaluation value for the test bill falls within the established statistical parameters, the test bill will be accepted by the bill handling machine. If the evaluation value for the test bill falls outside of the established statistical parameters, the test bill is determined to be a damaged bill and is not accepted by the bill handling machine.